SportsTurf provides current, practical and technical content on issues relevant to sports turf managers, including facilities managers. Most readers are athletic field managers from the professional level through parks and recreation, universities.
Issue link: http://read.dmtmag.com/i/638133
IRRIGATION & DRAINAGE 16 SportsTurf | March 2016 www.sportsturfonline.com FIELD SCIENCE ■ BY CHASE STRAW AND GERALD HENRY, PHD P erformance testing of sports fields is becoming more common to quantify surface properties, such as hardness. Many testing devices now incorporate a Global Positioning System (GPS) and Bluetooth capability to georeference field management loca- tions and send the data to a computer or tablet/phone device. Maps can be created from collected data using Geographic Information Systems (GIS) to visualize the variability (i.e. differences) of a certain property across a field. Maps are gaining increasing attention in the sports turf industry, with several private testing companies incorporating them in their consultation with sports turf managers. However, for you, the sports turf manager, little is known about how they are created and what their practical uses are. This article will discuss in general how maps are made, five ways maps can be used, and the future of maps in the sports turf industry. CREATING MAPS Maps are typically made from point data, where each point represents a specific latitudinal and longitudinal location on a field. Determining the latitude and longitude of a given point is called georeferencing and is done using a GPS device. Data that is collected at that location for a specific surface property can be stored within the point using Geographic Information System (GIS) software. Figure 1 depicts maps for five surface properties on a high school football field: volumetric water content (i.e. soil moisture), penetration resistance (i.e. soil compaction), normal- ized difference vegetative index (NDVI; i.e. turfgrass health), surface hardness, and turfgrass shear strength. The Google Earth images on the left show the points where data were collected and stored for each measured property. The soil moisture, soil com- paction, and turfgrass health data were collected using a mobile multi-sensor sampling device, the Toro Precision Sense 6000. The surface hardness and shear strength data were collected using a handheld Clegg Impact Tester and Shear Strength Tester, respec- tively. All point data were georeferenced using a GPS device. Once point data are collected, there are multiple methods to create maps using GIS software, all of which use some form of spatial interpolation. Spatial interpolation uses a mathematical formula that estimates values at locations that were not measured, based on the surrounding values at locations that were measured. The result is a continuous surface that shows the variability of a given property across the field, or in other words, a map (right side of Figure 1). Maps are not limited to these five properties. Any quan- tifiable measurement can be made into a spatially interpolated map. Now that you have a map, what can you do with it? Note: Maps can also be created using remote sensing techniques that include thermal heat or NDVI images. Maps made using remote sensing are often used in turfgrass management. Although this article will not discuss remote sensing maps, their application is similar to spatially interpolated maps. USING MAPS Implementing site-specific management. Site-specific management (also referred to as Precision Turfgrass Management) is perhaps the most commonly suggested use for maps in turfgrass. Site-specific management simply involves the application of inputs (such as water, aerification, and fertilization) only where, when, and in the amount needed. This MAPPING TO IMPROVE ATHLETIC FIELD MANAGEMENT